Project description:Complement receptor 2–negative (CR2/CD21–) B cells have been found enriched in patients with autoimmune diseases and in common variable immunodeficiency (CVID) patients who are prone to autoimmunity. However, the physiology of CD21–/lo B cells remains poorly characterized. We found that some rheumatoid arthritis (RA) patients also display an increased frequency of CD21–/lo B cells in their blood. A majority of CD21–/lo B cells from RA and CVID patients expressed germline autoreactive antibodies, which recognized nuclear and cytoplasmic structures. In addition, these B cells were unable to induce calcium flux, become activated, or proliferate in response to B-cell receptor and/or CD40 triggering, suggesting that these autoreactive B cells may be anergic. Moreover, gene array analyses of CD21–/lo B cells revealed molecules specifically expressed in these B cells and that are likely to induce their unresponsive stage. Thus, CD21–/lo B cells contain mostly autoreactive unresponsive clones, which express a specific set of molecules that may represent new biomarkers to identify anergic B cells in humans.
Project description:B cell tolerance is established using deletion, anergy and receptor editing mediated by secondary recombination but it is unclear why autoreactive B cells choose a tolerance mechanism over another. We identified subgroups of patients with either rheumatoid arthritis or common variable immunodeficiency who presented defects in secondary recombination, which correlated with unusual CD21-/lo naïve B cells in their blood. CD21-/lo B cells were unable to induce calcium flux, get activated or proliferate in response to B cell receptor and/or CD40 triggering, suggesting that these B cells are anergic. Moreover, CD21-/lo B cells are often autoreactive and may express anti-nuclear antibodies. Thus, anergy can be a default tolerance mechanism mainly induced when receptor editing fails to silence developing autoreactive B cells. Experiment Overall Design: RNA was extracted from batch sorted CD19+CD21+CD10-CD27- and CD19+CD21-CD10-CD27- naïve B cells isolated from donors using the Absolutely RNA microprep kit (Stratagene). 100-200 ng of RNA was obtained per sample, and the quality of the purified RNA was assessed by the Bioanalyzer from Agilent. Using the Ovation biotin system kit from Nugen, 30-50ng of RNA was amplified and labeled to produce cDNA. Labeled cDNA was hybridized on chips containing the whole human genome (Human Genome U133 2.0 from Affymetrix). Data from CD21+ and CD21- B cell populations were compared in order to determine the gene signature of the newly described CD21- B cells.
Project description:Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene segregates with most autoimmune diseases; its risk allele encodes overactive PTPN22 phosphatases that alter B cell receptor (BCR) signaling potentially involved in the regulation of central B cell tolerance. To assess whether PTPN22 risk allele affects the removal of developing autoreactive B cells, we tested by ELISA the reactivity of recombinant antibodies isolated from single B cells from asymptomatic healthy individuals carrying one or two PTPN22 risk allele(s). We found that new emigrant/transitional and mature naive B cells from PTPN22 risk allele carriers contained high frequencies of autoreactive clones compared to non-carrier control donors. Hence, a single PTPN22 risk allele has a dominant effect on altering autoreactive B cell counterselection, suggesting that early B cell tolerance checkpoint defects precede the onset of autoimmunity. In addition, gene array experiments comparing mature naïve B cells from healthy individuals carrying or not PTPN22 risk allele(s) revealed that the strength of association of PTPN22 for autoimmunity, second in importance only to the MHC, may not only be due to BCR signaling alteration but also to the regulation of other genes, which themselves have also been identified as involved in the development of autoimmune diseases. The PTPN22 risk allele is a single nucleotide change (cytidine to thymidine) at residue 1858, which results in a single amino acid substitution from arginine to tryptophan at position 620 of the PTPN22/Lyp protein. Data from mature naïve B cell populations from patients carrying 1 or 2 PTPN22 T alleles and non-carrier patients were compared in order to characterize the impact of PTPN22 polymorphism on B cell physiology. RNA was extracted from batch-sorted CD19+CD10-CD21+CD27- conventional mature naive B cells using the Absolutely RNA microprep kit (Stratagene). 100-200 ng of RNA was obtained per sample, and the quality of the purified RNA was assessed by the Bioanalyzer from Agilent. Using the Ovation biotin system kit from Nugen, 30-50ng of RNA was amplified and labeled to produce cDNA. Labeled cDNA was hybridized on chips containing the whole human genome (Human Genome U133 Plus 2.0 from Affymetrix).
Project description:Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IL-1R-associated kinase (IRAK)-4, myeloid differentiation factor 88 (MyD88) and UNC-93B. Indeed, all TLRs except TLR3 require IRAK-4 and MyD88 to signal and UNC-93B-deficient cells are unresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients did not display autoreactive antibodies in their serum nor developed autoimmune diseases, suggesting that IRAK-4, MyD88 and UNC-93B pathway blockade may thwart autoimmunity in humans. Experiment Overall Design: RNA was extracted from 105-3.105 batch sorted new emigrant and mature naïve B cells isolated from donors using the Absolutely RNA microprep kit (Stratagene). 100-200 ng of RNA was obtained per sample, and the quality of the purified RNA was assessed by the Bioanalyzer from Agilent. Using the Ovation biotin system kit from Nugen, 30-50ng of RNA was amplified and labeled to produce cDNA. Labeled cDNA was hybridized on chips containing the whole human genome (Human Genome U133 2.0 from Affymetrix). Raw data from new emigrant (1 healthy donor) and mature naive (4 healthy donors) B cells were analyzed in order to determine the expression of some molecules involved in the TLR pathway in these B cell population in humans.
Project description:<p>We identified germline heterozygous mutations in <i>CTLA4</i> in members of four families with severe immune dysregulation. Human <i>CTLA4</i> haploinsufficiency caused dysregulation of FoxP3+ regulatory T (Treg) cells and lymphocytic infiltration of target organs, mimicking <i>Ctla4</i> homozygous mice. Patients also exhibited a B cell phenotype, with progressive loss of B cells and accumulation of autoreactive CD21<sup>lo</sup> B cells. This study demonstrates a critical quantitative role for CTLA-4 in human immune homeostasis.</p>
Project description:Cells from porcine lymphoma tumors in the lymph node and spleen were cultured, cloned, and sequenced using Illumina next generation sequencing and compared to CD21+ or CD3+ splenocytes. Lymphoma clones were identified a B cell lymphomas by gene expression and surface marker presence.
Project description:Type I interferon (IFN), namely IFN- α, and B cell aberrations are long recognized in systemic lupus erythematosus (SLE) pathogenesis. Type I IFN receptor blockade has undergone clinical trials in SLE with varying degrees of success. Type III IFN (IFN-λ) produce a gene signature currently indistinguishable from that of type I in responsive cell types. IFN-λ are not blocked by type I IFN receptor blockade as they utilize a unique receptor (IFNLR1). Type III IFN are appreciated to have an important role in viral infection at epithelial barriers where IFNLR1 is strongly expressed. The effects of IFN-λ on immune cells remain understudied and are different between human and murine models. We have previously shown that human B cells can transcribe type I IFN genes after IFN-λ treatment including those associated with SLE. We have found that IFN-λ is detected in the serum of human SLE patients and correlates with IgD- CD27- CD21- CD24- (DN2) B cells, a compartment which contains CD11c+ age/autoimmunity B cells (ABC). ABC are a target of interest as recent studies suggest they are poised for plasma cell differentiation and enriched in autoreactivity and thus have the potential to contribute to SLE pathogenesis. Results: Naïve and DN cells display a prominent type I IFN gene expression profile in SLE. Transcript for type I, type II, and type III IFN receptors (IFNAR1, IFNAR2, IFNGR1, IFNGR2, IFNLR1, and IL10RB) are detected in HD and SLE B cells. CD11c+ CD21- frequency increased in DN compared to naïve B cells for SLE and HD (both p< 0.001). The mean and range of CD11c+ CD21- frequency was higher in SLE DN (30.7± 9.5%, mean±SEM; range 4.8-74.7%) compared to HD DN (7.6%±1.0%,3.6-9.4%). Increased IFNLR1 transcript correlated with CD11c+ CD21- B cell expansion (r2=0.922, p<0.0001). Increased pSTAT1 after IFN-α2 treatment is found in monocytes, T cells, and B cells but only in the B cells after IFN-λ1 treatment. Naïve, DN, switched, and unswitched memory HD B cells are responsive to type I and type III IFN, but demonstrated a higher pSTAT1 fold change with type I IFN treatment compared to type III IFN. In all B cell subsets, CD11c+ cells had a higher pSTAT1 fold change after IFN-λ1 stimulation than did CD11c- B cells. In HD with well-defined populations of CD11c+ CD21- DN cells, pSTAT1 fold change for IFN-λ approached that of IFN-α2. Conclusions: All human B cell subsets defined by CD27 and IgD respond to IFN-α and IFN-λ, but those expressing CD11c+ have increased responsiveness to IFN-λ. CD11c+ cells expand in SLE and associate with autoreactive plasma cell development. Thus, the role of IFN-λ may take on increased clinical significance in the setting type I IFN receptor blockade. These results suggest IFN-λ is an underappreciated driver of the IFN signature and B cell aberrations in SLE.
Project description:The homeostasis of circulating B cell subsets in the peripheral blood of healthy adults is well regulated, but in disease it can be severely disturbed. Thus, a subgroup of patients with common variable immunodeficiency (CVID) presents with an extraordinary expansion of an unusual B cell population characterized by the low expression of CD21. Since these circulating atypical B cells in the blood of CVID patients could not be assigned to any certain B cell differentiation stage in the periphery, they were designated as CD21low B cells. Although, CD21low B cells are polyclonal and unmutated IgM+IgD+ B cells like naive B cells in the peripheral blood, they reveal several distinct phenotypic and functional features. In order to uncover the the global programme of gene expression underlying these differences and changes in CD21low B cells we have performed microarray hybridization experiments and identified differentially expressed genes which define a distinct gene expression profile in CD21low B cells compared to naive B cells. Leucocytes were separated by Ficoll gradient from peripheral blood of healthy donors (HD) and CVID patients. CD19+CD27-CD38+CD21+ naive B cells of HD as well as naive and CD19hiCD27-CD38lowCD21low (CD21low) B cells of CVID patients were sorted using a MoFlow cell sorter. RNA was extracted from sorted ex vivo B cell subpopulations and hybridized on Affymetrix microarrays. Gene expression profiles were compared between CD21low B cells and naive B cells of CVID patients as well as HD naive B cells.
Project description:Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IL-1R-associated kinase (IRAK)-4, myeloid differentiation factor 88 (MyD88) and UNC-93B. Indeed, all TLRs except TLR3 require IRAK-4 and MyD88 to signal and UNC-93B-deficient cells are unresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients did not display autoreactive antibodies in their serum nor developed autoimmune diseases, suggesting that IRAK-4, MyD88 and UNC-93B pathway blockade may thwart autoimmunity in humans.
Project description:Protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene segregates with most autoimmune diseases; its risk allele encodes overactive PTPN22 phosphatases that alter B cell receptor (BCR) signaling potentially involved in the regulation of central B cell tolerance. To assess whether PTPN22 risk allele affects the removal of developing autoreactive B cells, we tested by ELISA the reactivity of recombinant antibodies isolated from single B cells from asymptomatic healthy individuals carrying one or two PTPN22 risk allele(s). We found that new emigrant/transitional and mature naive B cells from PTPN22 risk allele carriers contained high frequencies of autoreactive clones compared to non-carrier control donors. Hence, a single PTPN22 risk allele has a dominant effect on altering autoreactive B cell counterselection, suggesting that early B cell tolerance checkpoint defects precede the onset of autoimmunity. In addition, gene array experiments comparing mature naïve B cells from healthy individuals carrying or not PTPN22 risk allele(s) revealed that the strength of association of PTPN22 for autoimmunity, second in importance only to the MHC, may not only be due to BCR signaling alteration but also to the regulation of other genes, which themselves have also been identified as involved in the development of autoimmune diseases. The PTPN22 risk allele is a single nucleotide change (cytidine to thymidine) at residue 1858, which results in a single amino acid substitution from arginine to tryptophan at position 620 of the PTPN22/Lyp protein.